We've been doing some research on client-side Lightning pathfinding for Bark wallet apps. Instead of the Ark server working out the best payment route on the user's behalf, the wallet app builds the route and the payment onion itself, so the destination is not shared with the server and potentially eliminating minimum fees on Lightning transactions.

Full findings, link to proof of concept, and areas for further research: https://blog.second.tech/bark-client-side-pathfinding/